1. Field of the Invention
The present invention relates to a technical field of a phase locked state detecting apparatus and an information processing apparatus, particularly to a technical field of a phase locked state detecting apparatus for detecting a phase locked state of a signal which is phase controlled by a phase locked loop (PLL) circuit, and an information processing apparatus including the phase locked state detecting apparatus.
2. Description of Related Art
In recent years, an audio system has generally spread in which an information reproduction apparatus for reproducing music information from a compact disc (CD) is directly connected to an amplifier for amplifying and outputting the reproduced music information via a serial bus or another bus, and the reproduced music information is outputted to the outside via the amplifier.
In the amplifier in the audio system constituted as described above, a reference clock signal is generated based on time information transmitted with the reproduced music information. Then, a processing clock signal for use in a reproduction processing in the amplifier is set to a phase locked state based on the reference clock signal. The phase locked state means a state in which a phase of the reference clock signal accurately agrees with a phase of the processing clock signal. The processing clock signal maintaining this state is used to perform a necessary reproduction processing.
Moreover, this constitution accurately matches properties in data transmission of the information reproduction apparatus to those of the amplifier. For example, it matches properties of time information of the information reproduction apparatus to those of the amplifier. Therefore, while the information reproduction apparatus transmits the reproduced music information to the amplifier, it can amplify and output the reproduced music information.
In the conventional bus, however, depending on a bus type, when the information processing apparatus is newly connected to the bus, or when the connected information processing apparatus is disconnected from the bus, there may be cases where an initialization processing of temporarily initializing the information processing apparatus connected to the bus, and subsequently setting a new connection. For example, the initialization processing sets an information processing apparatus number for information transmission in the bus, or sets one information processing apparatus to generally control the information processing apparatuses interconnected via the bus with respect to the information transmission using the bus.
In this case, depending upon the bus type, the initialization processing includes an initialization processing requiring a long time for updating all connections in the information processing apparatuses connected to the bus (hereinafter referred to as long bus reset). The initialization processing also includes a short time initialization processing for performing the initialization processing similar to that of the long bus reset (hereinafter referred to as short bus reset).
On the other hand, the initialization processing is performed for the new connection of the information processing apparatus, even if the reproduction processing is executed in the amplifier. In this case, there is a problem that the music information being subjected to the reproduction processing is temporarily interrupted.